In modern mobile communication networks, such as second or third generation mobile radio networks, the users will in future be provided to an increased extent with additional services, “value added services”, besides the setting-up and maintenance of simple voice or data links. One important type of these value added services involves providing a user of the mobile radio network with the opportunity to retrieve data which are of interest to him from data stores and to download them to his mobile telephone, for example. The data can be text information, image information, audio data or film data, for example. Such data can also be provided by institutions which are independent of the operators of the mobile radio networks. Use of these value added services will often incur a cost for the mobile radio subscriber.